an edge between inside and outside is in fact the least likely proposition, because real galaxies don't have definite insides and outsides.
You've been there, so you know. There are cosmological models where the TREK "Barrier" would fit right in. Naturally, it will be a long time before we know for certain. And it is possible that such a Barrier is closer than the disc-plane edge of the Milky Way, but it would still be a great distance from Earth.